22 research outputs found
Insecticide resistance in Anopheles arabiensis from Ethiopia (2012-2016): a nationwide study for insecticide resistance monitoring.
BACKGROUND: Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) remain the cornerstones of malaria vector control. However, the development of insecticide resistance and its implications for operational failure of preventative strategies are of concern. The aim of this study was to characterize insecticide resistance among Anopheles arabiensis populations in Ethiopia and describe temporal and spatial patterns of resistance between 2012 and 2016. METHODS: Between 2012 and 2016, resistance status of An. arabiensis was assessed annually during the long rainy seasons in study sites from seven of the nine regions in Ethiopia. Insecticide resistance levels were measured with WHO susceptibility tests and CDC bottle bioassays using insecticides from four chemical classes (organochlorines, pyrethroids, organophosphates and carbamates), with minor variations in insecticides tested and assays conducted between years. In selected sites, CDC synergist assays were performed by pre-exposing mosquitoes to piperonyl butoxide (PBO). In 2015 and 2016, mosquitoes from DDT and deltamethrin bioassays were randomly selected, identified to species-level and screened for knockdown resistance (kdr) by PCR. RESULTS: Intense resistance to DDT and pyrethroids was pervasive across Ethiopia, consistent with historic use of DDT for IRS and concomitant increases in insecticide-treated net coverage over the last 15 years. Longitudinal resistance trends to malathion, bendiocarb, propoxur and pirimiphos-methyl corresponded to shifts in the national insecticide policy. By 2016, resistance to the latter two insecticides had emerged, with the potential to jeopardize future long-term effectiveness of vector control activities in these areas. Between 2015 and 2016, the West African (L1014F) kdr allele was detected in 74.1% (n = 686/926) of specimens, with frequencies ranging from 31 to 100% and 33 to 100% in survivors from DDT and deltamethrin bioassays, respectively. Restoration of mosquito susceptibility, following pre-exposure to PBO, along with a lack of association between kdr allele frequency and An. arabiensis mortality rate, both indicate metabolic and target-site mutation mechanisms are contributing to insecticide resistance. CONCLUSIONS: Data generated by this study will strengthen the National Malaria Control Programme's insecticide resistance management strategy to safeguard continued efficacy of IRS and other malaria control methods in Ethiopia
Most outdoor malaria transmission by behaviourally-resistant Anopheles arabiensis is mediated by mosquitoes that have previously been inside houses
Association of Khat and alcohol use with HIV infection and age at first sexual initiation among youths visiting HIV testing and counseling centers in Gamo-Gofa Zone, South West Ethiopia
Mapping insecticide resistance and characterization of resistance mechanisms in Anopheles arabiensis (Diptera: Culicidae) in Ethiopia
Monitoring changes in malaria epidemiology and effectiveness of interventions in Ethiopia and Uganda: Beyond Garki Project baseline survey
Assessment of mosquito larval productivity among different land use types for targeted malaria vector control in the western Kenya highlands
MOESM1 of Insecticide resistance in Anopheles arabiensis from Ethiopia (2012-2016): a nationwide study for insecticide resistance monitoring
Tables S1. Summary of PMI-supported IRS activities in Ethiopia, 2008-2016. Table S2. Summary of insecticide resistance assays conducted per year in Ethiopia, 2012-2016. Table S3. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in WHO susceptibility tests conducted in Ethiopia, 2013. Table S4. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in WHO susceptibility tests conducted in Ethiopia, 2014. Table S5. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in WHO susceptibility tests conducted in Ethiopia, 2015. Table S6. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in WHO susceptibility tests conducted in Ethiopia, 2016. Table S7. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in CDC bottle bioassays conducted in Ethiopia, 2013. Table S8. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in CDC bottle bioassays conducted in Ethiopia, 2014. Table S9. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in CDC bottle bioassays conducted in Ethiopia, 2015. Table S10. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in CDC bottle bioassays conducted in Ethiopia, 2016. Table S11. Percentage corrected mortality (and numbers tested) of Anopheles arabiensis in WHO susceptibility tests and CDC bottle bioassays conducted in Ziway Dugda, Ethiopia, 2013-2016